JPH10319916A - Liquid crystal display device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent an abnormal picture from being displayed when an irregular synchronizing signal is inputted at the time of supplying power or at a regular time. SOLUTION: A controller IC4 detects whether an inputted synchronizing signal satisfies prescribed setting conditions or not, when a synchronizing signal satisfying setting conditions is inputted, a picture is displayed based on picture data inputted in a liquid crystal panel 6. Also, when a synchronizing signal which does not satisfy setting conditions is inputted, a pattern signal previously incorporated in the controller IC4 is outputted, display such as a black screen in a whole screen and the like is performed based on the pattern signal.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a liquid crystal display device applied to an image display unit such as a personal computer and a monitor device, and more particularly to a dot matrix type TFT (Thin Film Transformer).
istor) This relates to a liquid crystal display module.

[0002]

2. Description of the Related Art FIGS. 4A and 4B are timing charts of a synchronizing signal input to a liquid crystal module, and FIG. 4B shows a part of the signal in FIG. It is a timing chart.

In general, a synchronization signal input to a liquid crystal module includes a vertical synchronization signal indicating a vertical scanning start timing, a horizontal synchronization signal indicating a horizontal scanning start timing, and a data enable signal indicating an effective data period. Input in synchronization with the signal.

In FIGS. 4 (a) and 4 (b), reference numeral 21 denotes a period (Tv) of a vertical synchronizing signal, during which a set number of horizontal synchronizing signal pulses are inputted. Reference numeral 22 denotes a period during which valid data is input, which is a vertical data valid period. twenty three
Is a period during which valid data is not input, and is called a vertical blanking period (Tvb).

Similarly, reference numeral 24 denotes the period of the horizontal synchronizing signal (T
h), 25 is the period during which valid data is entered,
This is the horizontal data valid period. 26 is a period during which valid data is not input, and is a horizontal blanking period (Thb).
Called.

Reference numeral 27 denotes a vertical data preparation period (Tve);
Is a horizontal data preparation period (The), which indicates a period from the detection of a synchronization signal to the input of valid data.

[0007] Unless any of the above-mentioned signals satisfies certain conditions, normal display cannot be performed on the liquid crystal display module. FIG. 5 is a diagram showing an example of specifications (setting conditions) of an input signal of a TFT liquid crystal display module generally used for a notebook type personal computer.
The maximum value (upper limit value) and the minimum value (lower limit value) are respectively defined. If a signal is input beyond the range between the upper limit value and the lower limit value, the liquid crystal display module cannot perform normal display.

[0008]

However, in the case of a notebook personal computer or a liquid crystal display monitor, not only at the time of turning on the power and at the time of resetting, but also at the time of changing the display resolution, changing the display color, and resuming. In various situations, such as in a power saving mode, a signal deviating from the specified specification may be input. Of course, most of the time is a few seconds or less, but during that few seconds, the previous screen looks like a burn-in screen or a noise-like screen, and abnormalities appear on the display. Image is displayed for a moment.

The reason will be described with reference to the timing chart of FIG. In FIG. 6, reference numeral 31 denotes a data enable signal at power-on, and reference numeral 32 denotes a timing of a clock during the same period. As can be seen from the figure, since the signal level is the ground level before the power is turned on, the amplitude of the signal gradually reaches a specified level from the moment the power is turned on. Also, the logic circuit in the liquid crystal display module may not operate normally until the power supply voltage is stabilized.

Therefore, the logics of the data enable signal and the clock which are actually recognized are expected to be in the signal states 33 and 34. Similarly, since the horizontal synchronizing signal and the vertical synchronizing signal are largely deviated from the original specifications, a normal image is not displayed for a certain period. Moreover, the abnormal display period greatly differs depending on the circuit configuration for supplying signals, the circuit configuration of the liquid crystal display module, and the like.

SUMMARY OF THE INVENTION An object of the present invention is to provide a liquid crystal display device which solves the above-mentioned conventional problems and detects an input signal and a power supply which are irregular so as not to display an abnormal image. To provide.

[0012]

In order to achieve the above object, the present invention comprises means for detecting whether or not an input synchronization signal satisfies a predetermined setting condition. During a period from time until the synchronization signal satisfies the setting condition, or after the synchronization signal satisfies the setting condition, during a period when the synchronization signal no longer satisfies the setting condition, a specific pattern is used. Means for displaying on the screen, or transmitting the signal of the detection result to the outside to perform appropriate processing, for example, when the input signal and the power supply are irregular. This also makes it possible to prevent an abnormal image from being displayed.

[0013]

BEST MODE FOR CARRYING OUT THE INVENTION
Means for detecting whether the input synchronization signal satisfies a predetermined setting condition, and a specific pattern during a period from power-on or reset until the synchronization signal satisfies the setting condition. Means for displaying an image on a screen, until a signal reaches a steady state within a predetermined range, displaying an image of a specific pattern so that an unpleasant and abnormal image is not displayed. To

According to a second aspect of the present invention, there is provided a means for detecting whether or not an input synchronization signal satisfies a predetermined setting condition, and means for detecting a synchronization after the synchronization signal satisfies the setting condition. Means for displaying a specific pattern on a screen during a period when the signal no longer satisfies the setting condition, even when the signal changes from a steady state to an abnormal state, during that time, an image of the specific pattern To prevent an unpleasant and abnormal image from being displayed.

According to a third aspect of the present invention, a means for detecting whether or not an input synchronization signal satisfies a predetermined setting condition, and a means for transmitting a signal of the detection result to the outside. When a signal is not in a steady state, it is possible to prevent an abnormal image from being displayed via an external member instead of displaying an image of a specific pattern.

Hereinafter, a preferred embodiment of the present invention will be described with reference to the drawings.

FIG. 1 is a block diagram showing a schematic configuration of a liquid crystal display device for explaining an embodiment of the present invention.
Is an input connector, 2 is a gate drive IC for supplying a signal to the gate line of the liquid crystal panel 6, 3 is a source drive IC for supplying a signal to the source line of the liquid crystal panel 6, and 4 is
Controller ICs 5 that process signals input to the input connector 1 and generate signals to be supplied to the gate driving IC 2 and the source driving IC 3 are liquid crystal display modules in which the above-described members are unitized.

The input connector 1 receives a vertical synchronizing signal, a horizontal synchronizing signal, a data enable signal, a clock signal, and a data signal as digital signals. The data signal generally has a 6-bit width of each of red, green, and blue, that is, 18 bits as a whole. The signal supplied to the input connector 1 is input to the controller IC 4 as it is, performs signal processing, and supplies necessary signals to the source driving IC 2 and the gate driving IC 3. The controller IC 4 generally has a function of inverting data for AC driving the liquid crystal, generating a clock of the gate / source driving IC, and generating a start signal for operating the shift register. In this example, the controller IC 4 has a function which is a feature of the present invention, which will be described later, in addition to the above function.

The specification of the input signal of the liquid crystal display module in the liquid crystal display device having the above configuration will be described. As described above, FIG. 4 shows signals input to the liquid crystal display module 5, and FIG. 5 shows specific numerical values of the timing in the horizontal and vertical periods.

For example, the period 21 in FIG. 4 represents the vertical cycle Tv, and needs to be in the range of 515Th to 535Th from FIG.
Here, Th represents a horizontal cycle. Similarly, reference numeral 26 denotes a horizontal blanking period Thb, which must be in the range of 150 Tclk to 170 Tclk from FIG. Here, Tclk represents a clock cycle.
As described above, the detailed timing of the input signal is all defined as shown in FIG. 5, and it is necessary to satisfy the specifications of this signal in order to display an image normally. Conversely, a signal that does not satisfy this specification may not be able to display a normal image.

FIG. 2 is a timing chart of a part of a signal input to the liquid crystal display module 5 (similar to a signal input to the controller IC 4) and a part of a signal recognized inside the controller IC 4 in this embodiment. It is shown. 11 shows a waveform from the power-on time of the data enable signal to each signal being stabilized, 12 shows a waveform from the power-on time of the clock signal to each signal being stabilized, and 13 and 14 show Each shows a data enable signal and a clock signal recognized inside the controller IC 4. In FIG. 2, for convenience of notation,
The horizontal cycle Th is only a few clocks long, but it is actually 80
It becomes 0 clock.

In FIG. 2, since the power gradually rises for a while (period 110) after the power is turned on, it can be seen that both the data enable signal and the clock signal have irregular waveforms inside the controller IC 4. on the other hand,
In the period 111, since the power supply voltage has sufficiently increased, both the data enable signal and the clock signal are normally recognized.

In the period 110, the signal is not recognized normally and does not satisfy the above-described setting condition of FIG. 5, so that when the data signal is displayed as it is, the screen becomes noise-like,
Not only cannot the intended image be displayed due to fluttering, but also an image apparently abnormal. Therefore, in this period 110, an image is not displayed on the basis of the input data signal, but is displayed on the screen in advance by displaying a pattern (all black display in this example) built in the controller IC 4 on the screen. Display that does not cause discomfort to the person watching the image. In addition,
As the pattern display, it is possible to display not only an entirely black screen but also, for example, an entirely white or blue image, or an arbitrary preset image such as a company name.

FIG. 3 shows a partial timing chart of another example of the signal input to the liquid crystal display module 5 shown in FIG. 1, similarly to FIG. 2. In the period 210, the signal is normally input. However, in the period 211, it is assumed that the signal generation timing is disturbed due to a change in the display mode of the personal computer which is the signal source of the liquid crystal display module 5. Further, in the period 212, the disturbance of the waveform is reduced, indicating that the input is normal.

Therefore, in the period 211, if an image is displayed as it is based on the input data signal, the image will be disturbed in the same manner as described above.
In the same manner as described with reference to FIGS. 1 and 2,
A pattern signal built in the controller IC 4 is output in advance, and an image is displayed based on the pattern signal. In other periods 210 and 212,
An image is displayed by processing and outputting the input data signal as usual.

As described above, according to the apparatus of this embodiment, when the synchronization signal is disturbed either at the time of turning on the power or after the power is turned on, the controller IC 4 determines that the signal is irregular based on the input synchronization signal. And a function of immediately switching to the built-in pattern signal and outputting the signal, it is possible to prevent display of an irregular image.

In the above embodiment, the controller I
In C4, it has been described that when detecting that the synchronization signal is irregular, the output signal is switched to display the built-in pattern signal. However, a part of the liquid crystal display module 5 indicates that the signal is irregular. A terminal or the like for receiving the detected result from the controller IC 4 and transmitting the detected result to the outside is provided, and the signal from the terminal is used as, for example, a signal for controlling the backlight of the liquid crystal panel 6 to turn on and off. When a signal is input, the backlight of the liquid crystal panel 6 may be turned off so that no image is displayed.

[0028]

As described above, according to the present invention,
During the period from power-on and reset to the time when the synchronization signal is supplied stably, and even when the synchronization signal is once stably supplied, if an invalid synchronization signal that does not meet the specifications is input. Can prevent display of a disturbed image, so that the practical effect is large.

[Brief description of the drawings]

FIG. 1 is a block diagram illustrating a schematic configuration of a liquid crystal display device for describing an embodiment of the present invention.

FIG. 2 is a timing chart showing a state of a part of a signal input to the liquid crystal display module of FIG. 1 and a state of a part of a signal recognized inside a controller.

FIG. 3 is a timing chart showing a state of a signal when the synchronization signal is once stabilized and then becomes an irregular state.

FIG. 4 is a timing chart showing a state of an input signal in a conventional example.

FIG. 5: TF commonly used for notebook computers
It is a figure showing an example of an input signal specification (setting conditions) of a T liquid crystal display module.

FIG. 6 is a timing chart showing states of a data enable signal and a clock signal when power is turned on.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Input connector, 2 ... Gate drive IC, 3 ... Source drive IC, 4 ... Controller IC, 5 ... Liquid crystal module, 6 ... Liquid crystal panel.

Claims (3)

[Claims] 1. A means for detecting whether or not an input synchronization signal satisfies a predetermined setting condition, and a period from power-on or reset until the synchronization signal satisfies the setting condition. Means for displaying a specific pattern on a screen. 2. A means for detecting whether an input synchronization signal satisfies a predetermined setting condition, and after the synchronization signal satisfies the setting condition, sets the synchronization signal to the setting condition. Means for displaying a specific pattern on a screen during a period in which the condition is not satisfied. 3. A device comprising: means for detecting whether an input synchronization signal satisfies a predetermined setting condition; and means for transmitting a signal of the detection result to the outside. Liquid crystal display device.